In a disk device, such as a magnetic disk device, an optical disk device and a magneto-optical disk device, the information recording density can be improved with a smaller distance between the recording layer of the disk and the recording/reproducing device of the head slider. Accordingly, the flying amount of the head slider is being decreased along with improvement in information recording density of the disk device.
For example, in order to improve an information recording density of a magnetic disk, it is necessary to decrease the distance between the recording/reproducing device mounted on the magnetic head slider and the magnetic film constituted by sputtering or the like on the magnetic disk surface, so-called a magnetic spacing. In a current magnetic disk device, a DLC (diamond like carbon) protective film is constituted on the magnetic disk, and a lubricant is further coated on the DLC protective film. A DLC protective film is also constituted on a rail surface of a flying surface of the magnetic head slider. The flying height of the magnetic head slider on the magnetic disk, i.e., the distance (clearance) between the DLC protective film of the magnetic disk and the flying lowermost point of the magnetic head slider upon flying is being reduced to a level below about 10 nm in terms of design value.
In a disk device having a head slider flying at an extremely low height, there is substantially no margin on flying the head slider in consideration of fluctuation in flying height due to change in temperature and atmospheric pressure inside the disk device and around the disk device, and the like. Accordingly, occurrence of contact between the disk and the head slider due to the disturbance in temperature and atmospheric pressure is unavoidable.
The contact between the disk and the head slider in the disk device may bring about, in addition to physical breakage of the disk device (crash), attachment of the lubricant coated on the disk or contamination generated by friction between the disk and the head slider onto the flying surface of the head slider, particularly onto the step bearing surface or the negative pressure groove surface thereof. In the current magnetic disk slider, which flies on the magnetic disk with the balance between positive pressure and negative pressure generated by the flying surface of the slider, in most cases the lubricant and contamination are attached onto the step bearing surface, at which the air flow rate is decreased, and the deep groove surface, at which negative pressure is generated. In the case where the lubricant or contamination is attached onto the step bearing surface or the negative pressure groove surface, the flying amount is increased by increasing the positive pressure or decreasing the negative pressure on the air-bearing surface between the slider and the disk, and the rigidity of the air film is decreased to destabilize the flying. The destabilization in flying of the slider induces contact between the disk and slider to provide such a possibility of causing physical is breakage (crash), which may become a factor of considerably decreasing the reliability of the magnetic disk device. Accordingly, it is necessary to suppress the lubricant and contamination from being attached onto the flying surface of the head slider, particularly onto the air-bearing surface or the negative pressure groove surface thereof.
In view of the problem, there have been disclosed a technique of providing protrusions on a flying surface to decrease a contact area between a disk and a head slider, and a technique of providing a carbon protective film as a thin film having fluorine ions implanted therein, on a surface of a magnetic head slider facing a magnetic disk, whereby the friction force upon contacting is decreased to stabilize the flying of the slider, as disclosed in Japanese Patent Publication No. 8-147655 (“Patent Document 1”).
The technique of implanting ions in a flying surface of a magnetic head slider has an effect of suppressing a lubricant and contamination (such as dusts) from being attached onto the magnetic head slider since lipophobicity obtained by decreasing the surface energy of the slider flying surface, as having been described above.
However, upon implanting fluorine ions as in Patent Document 1, the surface roughness on the flying surface of the magnetic head slider is increased. FIG. 3 shows, in the flying surface of the magnetic head slider having fluorine ions implanted therein, (a) the result 14 where the front rail surface is measured with an intermolecular force microscope (AFM) and (b) the result 15 where the center rail surface is measured with an intermolecular force microscope (AFM). In the magnetic head slider, the material of the slider part is constituted by AlTiC, and therefore, the front rail and the center rail are constituted in the AlTiC part. In FIGS. 3(a) and (b), particle boundaries of TiC particles 16, which have not been confirmed before implanting ions, are clearly confirmed. This is because the protective film on the flying surface of the slider is sputtered due to the sputtering effect of ion implantation, whereby AlTiC as an underlayer is partially exposed. The surface roughness due to the particle boundaries has a size equivalent to the flying clearance having been described above, and therefore, reduction in flying height of the head slider is impaired when the ion implantation is effected on the whole surface as in Patent Document 1.
Associated with a decrease in flying height of a magnetic head slider, there arises a problem of destabilization of flying of a slider due to attachment of contamination to a flying surface of a magnetic head slider.